The main advantage of the techniques, using photon conversion is that conversion processes and devices can be considered and optimized independently, without affecting the particular physical properties of the operating photovoltaic material or device architectures. An important feature of organic solar cells is the limited spectral range of absorption in organic dye molecules / polymers. The most efficient solar cells at present are harvesting blue, green, and /or red parts of the solar spectrum. Up to now the triplet-triplet annihilation-supported upconversion (TTA–UC) is the only upconversion process excited with moderate concentrated sunlight. Our group demonstrates UCd based on family of symmetrical tetraaryltetraanthra[2,3]porphyrins sensitizers, bearing various substituents in meso-phenyls and anthracene residues. The multicomponent organic system PdTAP’s/Rubrene/toluene demonstrates UC–fluorescence with quantum yield on the level of 0.03. This UC-molecular system efficiently transforms the IR-A part of the sun spectrum into the VIS-range, operating under moderate concentrated sunlight (50 suns, AM1.5). The next important requirement is the protection of UC-molecular system from the ambient oxygen. Our group demonstrates oxygen scavenging formulations, well-suited for the TTA–UC process. Compatibility between the UC device and the photovoltaic device, including the subject of optical coupling is discussed.